Display screen or portion thereof with an animated graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with a first image in a sequence for an animated graphical user interface; and,

FIG. 2 is a front view of a display screen or portion thereof with a second image in a sequence for an animated graphical user interface.

The outermost long and short dashed broken lines illustrate a display screen or portion thereof and form no part of the claimed design. The remaining broken lines, illustrating portions of the animated graphical user interface, form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an animated graphical user interface, as shown and described. 